Abstract 242: Analysis of temozolomide-loaded CLENs for treatment of human glioblastoma multiforme in vitro

Abstract

Abstract Introduction: Glioblastoma multiforme (GBM) is the most prevalent neoplasm of the central nervous system, and has a 100 percent mortality rate despite current standard of care. We previously reported the use of cell membrane lipid-extracted nanoliposomes (CLENs) for tumor targeting. The approach involved the extraction of lipids directly from breast cancer cell membranes to develop nanoliposomes to efficiently target the same cell population from which the lipids were derived. This current study involves the development of CLENs for treatment of drug resistance in GBM, based on optimized formulation properties from our research involving breast cancer. Methods: Three liposome preparations were formulated with either U87-MG (human GBM) cell line membrane lipid extract (LE), DSPE-PEG5000 (PEG), or both, in addition to conventional components. The specific formulations contain DOPC, Cholesterol, LE, and PEG at ratios of 60/25/10/5 (Prep 1), 65/25/10/0 (Prep 2), and 70/25/0/5 (Prep 3), respectively. Temozolomide (TMZ) drug loading studies were determined by UV-spectroscopy. Cellular uptake of liposome preparations by U87-MG was determined with fluorescence intensity values using rhodamine-labeled liposomes in vitro. Cytotoxicity analysis of TMZ-loaded liposome preparations was evaluated using a sulforhodamine B (SRB) cytotoxicity assay. Results: Liposome preparations were characterized for mean particle size (nm) and surface charge (mv) in the presence and absence of incorporated TMZ. Average particle size for formulations loaded with TMZ were 148 nm (Prep 1), 221 nm (Prep 2), and 153 nm (Prep 3), which were not significantly different from preparations without incorporated drug, 149 nm, 217 nm, and 148 nm, respectively. Average zeta potential values for formulations loaded with TMZ were 3.3 mV (Prep 1), -2.7 mV (Prep 2), and -7.9 mV (Prep 3). For preparations without TMZ, values were -5.1 mV (Prep 1), -3.1 mV (Prep 2), and -5.8 mV (Prep 3). Cellular uptake studies suggested that the inclusion of LE had no effect on uptake of the liposomes by U87-MG target cells, with minimal effect on cytotoxicity. Moreover, the cytotoxicity conferred by the preparation containing PEG in the absence of LE (Prep 3) was consistent with a greater drug-incorporation efficiency than Prep 1. Conclusion: The role of LE incorporation for selective tumor targeting involving CLENs developed for GBM remains unclear, and seems to confer diminished cytotoxicity and formulation properties, when compared to favorable findings involving use of breast cancer cell lines published elsewhere. It is thus possible that the inclusion of LE in nanoliposomes for brain cancer may require more personalized optimization in relation to the brain tissue environment over the use of more standard or shared formulation considerations studied in other organ tissues. Optimization studies involving CLENs to test the theory are currently underway. Citation Format: Alexander Arau, Ilia Pidroutchniak, Woong Jae Song, Robert Campbell. Analysis of temozolomide-loaded CLENs for treatment of human glioblastoma multiforme in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 242.